1. Technical Field
One or more embodiments of the present invention generally relate to at least one multi-diameter unplugged component hole on a printed circuit board.
2. Background Art
A PCB is generally flat, and is a multi-layer board made of fiberglass with copper tracks extending between the layers of the board. The PCB includes a plurality of component holes that connect the copper tracks from one layer of the board to other layers of the board. The component holes generally extend from a top surface of the board to a bottom surface of the board. Each component hole is cylindrical and includes a constant diameter therethrough (e.g., from the top surface of the PCB to the bottom surface of the PCB). Each component hole is configured to receive a lead of an electronic component (or through-hole electrical component). The lead of the electronic component may include a cross section that is cylindrical, square shaped, trapezoidal, or rectangular. Each component hole couples the lead to a corresponding track in a corresponding layer of the PCB. Solder is applied to the component hole to fixedly couple the lead of the electronic component to the corresponding track(s) of the PCB and to facilitate electrical communication therethrough.
It is also known that PCBs may include a plurality of pads positioned on the top surface that connect the copper tracks from one layer of the board to other layers of the board. A surface mount device (SMD) may be positioned on top of the pad (or lie on top of the pad). The pad is generally solid and fixedly couples the SMD to the corresponding track with solder to facilitate electrical communication between the SMD and the tracks. The process of coupling the SMDs and the through-hole electrical components to the PCB generally include two solder operations.
In a first operation, solder paste is applied to the pads of the PCB to temporarily hold the SMDs to corresponding pads. After the solder paste is applied, the PCBs with the SMDs positioned thereon are subjected to a reflow soldering process. The reflow soldering process generally includes applying heat in a controlled manner to solder the SMDs to the pads of the PCB. The source of the heat applied in the reflow process may include one or more of infrared lamp, oven, or hot air pencil.
In a second operation, the through-hole electrical components are inserted into corresponding component holes of the PCBs. Solder paste is generally applied to each component hole to temporarily hold the through-hole electrical components therein. The PCB with the through-hole electrical components is then drawn over the surface of a pool of molten solder in which all of the through-hole electronics are soldered to the component holes of the PCB at once. Such a process is known as a wave solder. Areas on the PCB around the component holes that do not need solder are protected by a solder mask. While the first and second operations are generally useful in soldering PCBs equipped with SMDs and through-hole electrical components, the second operation adds cycle time to the manufacturing process of generating a populated and soldered PCB. Further, the second operation may expose the through-hole electrical components and the SMDs to higher temperatures than that of the reflow solder process. Such exposure to increased levels of thermal exposure may decrease reliability.